Space Tug

Currently, when satellites malfunction, they become (very expensive) space junk. A geosynchronous satellite orbits at 36,000 km (22,300 miles), which puts it outside the range for any type of service or repair. But researchers at Queen’s University in Kingston, Ontario are hoping to change that.

“These are mechanical systems, which means that eventually they will fail,” notes Electrical and Computer Engineering professor Michael Greenspan, who leads the Queen’s project. But because they are many thousands of kilometres away, the satellites are beyond the reach of an expensive, manned spaced flight, while Earth-based telerobotic repair isn’t possible in real time."

Dr. Greenspan’s solution to this problem is the development of tracking software that will enable an Autonomous Space Servicing Vehicle (ASSV) to grasp the ailing satellite from its orbit and draw it into the repair vehicle’s bay. Once there, remote control from the ground station can be used for the repair, he explains. “The repair itself doesn’t have to be done in real time, since everything is in a fixed position and a human can interact with it telerobotically to do whatever is required.”

The main challenge in this process is computer vision. The robotic system must be able to recognize and track the satellite, even in the harsh illumination conditions of space. Here’s a video demonstration of the technology that helps accurately measure the surface geometry of the satellite. It’s a light-based radar called LIDAR:


Funding for the Queen’s University research is provided by NSERC. NSERC is a federal agency whose vision is to help make Canada a country of discoverers and innovators for the benefit of all Canadians. The agency supports some 25,000 university students and postdoctoral fellows in their advanced studies and promotes discovery by funding more than 11,000 university professors every year.


Loral tried to sell NASA on a space tug last December:

Instead of using a Russian Progress supply spacecraft to retrieve a separately launched pressurized cargo vehicle and guide it back to the space station for unloading, the Space System/Loral-team would use the company’s proven 1300-series satellite bus as a refuelable space tug that would remain in orbit for as long as 10 years.

And then, of course, there’s the Jules Verne cargo ship, which we’ve blogged about before.